JP4770619B2 - Display image correction apparatus, image display apparatus, and display image correction method - Google Patents

Display image correction apparatus, image display apparatus, and display image correction method Download PDF

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JP4770619B2
JP4770619B2 JP2006196669A JP2006196669A JP4770619B2 JP 4770619 B2 JP4770619 B2 JP 4770619B2 JP 2006196669 A JP2006196669 A JP 2006196669A JP 2006196669 A JP2006196669 A JP 2006196669A JP 4770619 B2 JP4770619 B2 JP 4770619B2
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correction amount
correction
video signal
amount data
image
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JP2007122013A (en
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義樹 城地
裕 山形
俊成 渕上
旭 白浜
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ソニー株式会社
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N17/00Diagnosis, testing or measuring for television systems or their details
    • H04N17/04Diagnosis, testing or measuring for television systems or their details for receivers
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00Control of display operating conditions
    • G09G2320/02Improving the quality of display appearance
    • G09G2320/0233Improving the luminance or brightness uniformity across the screen
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00Control of display operating conditions
    • G09G2320/02Improving the quality of display appearance
    • G09G2320/0285Improving the quality of display appearance using tables for spatial correction of display data
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00Control of display operating conditions
    • G09G2320/06Adjustment of display parameters
    • G09G2320/0673Adjustment of display parameters for control of gamma adjustment, e.g. selecting another gamma curve
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00Control of display operating conditions
    • G09G2320/06Adjustment of display parameters
    • G09G2320/0693Calibration of display systems
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/2007Display of intermediate tones
    • G09G3/2044Display of intermediate tones using dithering
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/2007Display of intermediate tones
    • G09G3/2059Display of intermediate tones using error diffusion
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406Control of illumination source

Description

  The present invention relates to a display image correction apparatus and a method for correcting a video signal in order to correct a predetermined deterioration factor of a displayed image. The present invention also relates to an image display apparatus to which the configuration of such a display image correction apparatus and method is applied.

  In an image display device that displays an image by a video signal, for example, due to structural problems or manufacturing variations, the uniformity of the luminance distribution in the image region displayed on the screen is impaired. A phenomenon called so-called luminance unevenness may occur. Such luminance unevenness is a factor in image quality deterioration. In particular, in the case of color image display, since chromaticity unevenness is also generated, it is required to be eliminated or suppressed. . Therefore, for example, as shown in Patent Document 1, a configuration for correcting luminance unevenness has been proposed.

JP 2001-231053 A

  The present invention also proposes a configuration for correcting the luminance unevenness of the display image, and an object thereof is to perform the correction of the luminance unevenness more efficiently than before.

In view of the above problems, the present invention is configured as a display image correction apparatus as follows.
In other words, it is data for correcting luminance non-uniformity for an image displayed based on a digital video signal, and is set in advance in the image obtained in accordance with the level of the reference video signal. A holding means for holding reference correction amount data, which is data indicating correction amounts of horizontal / vertical positions as a plurality of reference correction points, and correction processing of the video signal according to the horizontal / vertical direction and the luminance direction in the image. performs linear two-dimensional correction amount data corresponding to the horizontal / vertical position obtained by weighting the reference correction amount data at reference correction points adjacent to the horizontal / vertical direction on the image to the level of the corrected video signal Corrects non-uniformity in brightness of the image based on three-dimensional correction amount data, which is correction amount data for each pixel forming the image obtained in proportion. Correction means for performing correction processing for the two-dimensional correction amount data in an addition / subtraction format obtained based on the reference correction amount data for the video signal to be corrected And an adder that adds the three-dimensional correction amount data that is the output of the multiplier and the video signal to be corrected, and the output of the adder is used as a corrected video signal. It was decided to be configured to output as

Further, the image display device is configured as follows.
First, an image display device according to the present invention includes a display image correction device unit and a display device unit that displays an image based on a video signal subjected to correction processing by the display image correction device.
In addition, the display image correction device unit is data for correcting luminance non-uniformity for an image displayed based on the digital video signal, and is obtained corresponding to the level of the reference video signal. According to the horizontal / vertical direction and the luminance direction of the image, holding means for holding reference correction amount data that is data indicating correction amounts of horizontal / vertical positions that are a plurality of preset reference correction points in the image. The video signal correction process is performed, and the two-dimensional correction amount data corresponding to the horizontal / vertical position obtained by weighting the reference correction amount data at the reference correction points adjacent to the image in the horizontal / vertical direction is corrected. The brightness of the image is determined based on three-dimensional correction amount data that is correction amount data for each pixel forming the image, which is obtained by linearly proportional to the level of the video signal. Correction means for performing a correction process for correcting non-uniformity with respect to the image signal, and the correction means is an addition / subtraction format obtained based on the reference correction amount data for the video signal to be corrected A multiplier that multiplies the two-dimensional correction amount data; an adder that adds the three-dimensional correction amount data that is an output of the multiplier and the video signal to be corrected; and an output of the adder Is configured to be output as a corrected video signal.

In each of the above-described configurations, for correcting the non-uniformity of the two-dimensional luminance in the image displayed on the display screen, which is called luminance unevenness, for example, first, it corresponds to the reference video signal level (brightness). The reference correction amount data, which is the data indicating the correction amount of the predetermined horizontal / vertical position in the image obtained in this way, is held. At the time of correction, a two-dimensional correction amount corresponding to the horizontal / vertical position is obtained based on the reference correction amount data, and the two-dimensional correction amount is proportional to the luminance of the video signal to be corrected. The video signal is corrected according to the obtained three-dimensional correction amount.
In such a configuration for correction, the reference correction amount data includes only data corresponding to a predetermined reference video signal level, and correction processing adapted to the luminance of the video signal is possible. Has been. In other words, the correction for luminance unevenness can be appropriately executed in accordance with the luminance of the video signal, but the data for correction is the same number as before for the data corresponding to the luminance direction. Means that there is no need to prepare.

  In this way, according to the present invention, it is possible to prepare and store only the correction amount data (reference correction amount data) for correcting luminance unevenness according to the reference video signal level. As a result, the storage capacity required to actually store and hold the correction amount data is compared with the case where a plurality of data more than a predetermined number corresponding to the brightness (for example, luminance) direction is provided. , Can be less. Thereby, for example, the memory capacity necessary for actually storing the correction amount data can be reduced, and the cost can be effectively reduced. In addition, when adjusting the correction amount data at the time of manufacturing, etc., the adjustment time is shortened because only the correction amount data corresponding to the luminance direction, which is smaller than before, has to be performed. The production efficiency will be improved. In addition, such improvement in production efficiency leads to cost reduction.

FIG. 1 shows a configuration of a television receiver to which a display image correction apparatus and an image display apparatus according to an embodiment of the present invention are applied.
In the television receiver 1 shown in this figure, the broadcast wave received by the antenna 10 is input to the tuner 11. The tuner 11 performs carrier demodulation or the like on the input received wave, extracts and acquires a video signal of a designated channel, for example, under the control of the control unit 19, and outputs it to the decoder 12. In the decoder 12, for example, when the input video signal is scrambled or the like, the decoder 12 performs a demodulation process for solving the scramble. In the present embodiment, the video signal processing is executed by the digital signal processing of the video signal processing unit 16 at the subsequent stage, so that a digital video signal is output from the decoder 12. It shall be.

  In this case, by providing the video input terminal 13, a video signal output from an external video device or the like can be input. A video signal of a predetermined format input to the video input terminal 13 is input to the analog decoder 14. The analog decoder 14 converts the input video signal into a digital video signal having a predetermined format when the signal is an analog predetermined format.

  The digital video signal output from the decoder 12 is output to the terminal T2 of the switch 15, and the digital video signal output from the analog decoder 14 is output to the terminal T3 of the switch 15. . The switch 15 is provided for selecting an input video source, and is switched so that one of the terminals T2 and T3 and the terminal T1 are connected in accordance with the control of the control unit 19. . In a state where the terminal T2 is connected to the terminal T1, the digital video signal output from the decoder 12 is input to the video signal processing unit 16. That is, the broadcast program selected for reception is selected as the input video source. When the terminal T3 is connected to the terminal T1, the digital video signal output from the analog decoder 14 is input to the video signal processing unit 16. That is, a video signal input from an external device is selected as an input video source.

  The video signal processing unit 16 executes various necessary signal processings such as resolution conversion for converting the number of pixels of the input digital video signal into the number of pixels of the display panel of the liquid crystal display unit 18 and image quality adjustment. To do. The video signal processing unit 16 is also configured to execute a correction process for the video signal for correcting the luminance unevenness of the image.

The video signal output from the video signal processing unit 16 is input to the display driver 17. The display driver 17 drives the liquid crystal display unit 18 to display using the input video signal. As a result, an image corresponding to the video signal is displayed on the display screen of the liquid crystal display unit 18.
The liquid crystal display unit 18 is an image display part configured to include a liquid crystal as a display device.
Note that although the television receiver can actually reproduce and output audio together with the received broadcast program or the video signal of the external input source, the illustration and explanation of the audio reproduction system are omitted here.

The control unit 19 is configured to include, for example, a microcomputer formed by combining a CPU (Central Processing Unit), a ROM, a RAM, and the like, and executes control on each of the above-described parts in the television receiver 1. The
For example, when a video signal that has been scrambled and broadcast is input to the decoder 12, the control unit 19 can control signal processing for canceling the scramble.
In addition, the control unit 19 executes signal processing that conforms to the difference in the method between the standard resolution (SD: Standard Definition) for the input video signal and the high-definition resolution (HD: High Definition) such as high definition. Control to do this is also performed.
In addition, as described above, the control unit 19 switches between when the broadcast source is to be displayed and when the input source from the video input terminal 13 is to be displayed in response to, for example, an operation of selecting a video source. The switching control for 15 is also executed.
Further, the analog decoder 14 is controlled so that an appropriate digital signal conversion process is executed in accordance with a method such as HD / SD of a signal input from the video input terminal 13.

In addition, the control unit 19 controls the video signal processing unit 16 for necessary signal processing operations including the resolution conversion, image quality adjustment, luminance unevenness correction, and the like.
In the present embodiment, in particular, for luminance unevenness correction, a reference held in a non-volatile storage area (for example, a storage area such as a ROM, an EEPROM, or a flash memory) provided in the control unit 19. The information in the correction amount table 19a is used. As will be described later, this reference correction amount table is a set of two-dimensional correction data in which the correction amount value of the reference correction point in the two-dimensional direction of the screen is indicated corresponding to one reference luminance. It is said.
When the luminance unevenness correction signal processing is executed, the control unit 19 acquires the three-dimensional correction amount from the reference correction amount table 19a according to the luminance unevenness correction processing timing in the video signal processing unit 16. The data of the correction amount of the reference correction point necessary for the transfer is transferred to the video signal processing unit 16. Note that the three-dimensional correction amount data means correction amount data having a correction amount component in the luminance (brightness) direction in addition to two-dimensional in the horizontal / vertical direction of the screen, as will be described later. The video signal processing unit 16 obtains three-dimensional correction amount data by using the correction amount data of the reference correction point, and performs correction processing on the video signal by using the three-dimensional correction amount data. Thus, processing as luminance unevenness correction is realized. A configuration in which the processing for obtaining the three-dimensional correction amount is obtained by the arithmetic processing of the CPU in the control unit 19 and transmitted to the signal processing system for correcting the luminance unevenness of the video signal processing unit 16 is also conceivable. However, the process for obtaining the three-dimensional correction amount from the two-dimensional correction amount is a relatively heavy process, and may give a certain processing load to the microcomputer provided in the control unit 19 in some cases. Therefore, in the present embodiment, in consideration of this, the video signal processing unit 16 side is caused to execute a process for obtaining a three-dimensional correction amount.

Next, luminance unevenness correction according to this embodiment will be described.
Generally, luminance unevenness refers to luminance non-uniformity when an image displayed on a display screen is observed in a two-dimensional direction. In order to correct this luminance unevenness, correction data having a correction amount adjusted according to the state of luminance unevenness in the actual image is created, and this correction data is stored and held in a device such as a display device. Then, a device such as a display device calls correction data stored and held to execute correction processing on the video signal. As a result, the luminance level of the video signal is adjusted so as to cancel the luminance unevenness, and the luminance unevenness is actually corrected for the display image.

Here, a general description of correction data for correcting luminance unevenness will be given.
First, luminance unevenness is non-uniformity of luminance in a two-dimensional space in the horizontal / vertical direction of an image displayed on a display screen, and thus correction data indicating a correction amount corresponding to the two-dimensional space is necessary. Become. Such two-dimensional correction data will be described with reference to FIG.

  As shown in this figure, in obtaining two-dimensional correction data, a two-dimensional space as one display screen (image) is divided into an X direction (horizontal direction) and a Y direction (vertical direction) on the image. Each of the lines is divided by a dividing line set in correspondence with a predetermined unit of pixel number (N, M). Next, on this display screen, coordinates of 0 to p are given in the X direction in correspondence with the contour lines and the dividing lines of the screen in the horizontal (X) / vertical (Y) direction, as shown in the figure. Give 0 to q coordinates in the direction. A reference correction point (reference correction point) indicated as C (0,0), C (0,1)... C (p, q) is set for each of the intersections of these coordinates. Is done. In this case, (p + 1) × (q + 1) reference correction points are set. Then, for example, the luminance is measured for each reference correction point of the display screen set as described above under the luminance level of the video signal under a certain condition, and the correction amount for each reference correction point is determined according to the measurement result. Set. A two-dimensional set of correction amounts set in this way becomes two-dimensional correction data corresponding to one luminance level.

Then, by obtaining two-dimensional correction data using the data obtained in this way, luminance unevenness correction is performed with the pixel unit for forming the display image shown in FIG. 2 as a correction point. Is done.
For this purpose, the display screen shown in FIG. 2 is divided and set into a rectangular space region (region between reference correction points) formed by connecting four reference correction points adjacent in the horizontal / vertical direction. Based on the fact that (p × q) regions between the reference correction points are formed, here, the regions between the reference correction points are [1, 1] [1, 2]. q].
As an example, it is assumed that luminance unevenness is corrected using the pixel dxy in the region [5, 3] between the reference correction points in FIG. 2 as a correction point. For this purpose, for example, first, reference correction points C (4, 2), C (5, 2), C (4, 3), C (5 , 3) specifies the distance of the pixel dxy from. Then, the correction amounts of the reference correction points C (4,2), C (5,2), C (4,3), and C (5,3) are weighted according to the specified distance. By performing a predetermined calculation, the amount of correction of the position of the pixel dxy is obtained. That is, the correction amount of the correction point as the pixel dxy uses the correction amounts of the reference correction points C (4,2), C (5,2), C (4,3), and C (5,3). Obtained by interpolation. Correction processing is performed on the luminance level of the sample of the video signal corresponding to the pixel dxy with the correction amount obtained in this way. As a result, in the pixel dxy, display is performed with a luminance that cancels the luminance unevenness.

FIG. 3 simply shows the structure of a liquid crystal display device corresponding to the liquid crystal display unit 18 of the present embodiment. As described above, the liquid crystal display device includes a liquid crystal panel and a backlight unit disposed on the back side thereof. Let us consider correcting the luminance unevenness of the liquid crystal display device using the two-dimensional correction data described with reference to FIG.
Here, it is assumed that the backlight unit is one light source having a planar shape corresponding to the shape of the liquid crystal panel, and light emission positions P1 and P2 in the two-dimensional planar light source are assumed. It is assumed that light is emitted at luminance (light emission luminance) A at the light emission position P1, while light is emitted at light emission luminance A-dA at the light emission position P2. That is, when the light emission position P1 is considered as a reference, the light emission position P2 has an error in light emission luminance of an amount represented by −dA.

The light having the light emission luminances A and A-dA emitted from the light emission positions P1 and P2 passes through the LCD panel and is observed as the luminance (observation luminance) y. This observed luminance y is expressed by the following (Equation 1) by an index γ based on the transmittance of the liquid crystal panel and a drive voltage x applied to drive the liquid crystal panel.
Further, based on (Equation 1), the observed luminance y1 observed on the liquid crystal panel corresponding to the light emission position P1 of the emission luminance A is expressed by the following (Equation 2).
Since one light emission position P2 emits light with the light emission luminance A-dA, it has an error of -dA light emission luminance with respect to the light emission luminance A at the light emission position P1. The -dA light emission luminance difference between the light emission positions P1 and P2 appears as a difference in observation luminance obtained by transmitting through the liquid crystal panel, that is, luminance unevenness. Therefore, if the observation luminance corresponding to the light emission position P2 is to be corrected so as to be the same as the observation luminance corresponding to the light emission position P1, the voltage represented by x + dx with the correction amount dx added to the drive voltage x is calculated. Will be applied. The observed luminance y2 corresponding to the light emission position P2 obtained by performing correction in this way is expressed by the following (Equation 3).
And the brightness nonuniformity correction here is about observation brightness | luminance y1, y2.
y1 = y2
Means to establish. Based on this, the following (Equation 4) is established by the above (Equation 2) and (Equation 3).
Further, when the above (Equation 4) is solved for dx, the following (Equation 5) is obtained.
Further, when the drive voltage correction amount corresponding to the light emission position P2 obtained when the drive voltage x = 1 is set to dx (max), the above (Equation 5) is expressed as the following (Equation 6). It is expressed as
From the relationship between (Equation 6) and (Equation 5), the drive voltage correction amount dx is expressed by the following (Equation 7).
This (Equation 7) indicates that the correction amount dx is proportional to the drive voltage x.

Theoretically, the correction amount dx for each luminance is proportional to the drive voltage x as described above. However, in reality, it is known that good results are not always obtained when correction based on (Equation 7) is performed.
One reason for this is that there is a limit in resolution when digital signal processing is performed on a video signal.
In addition, the correction between the observation luminances y1 and y2 described above deals with only the luminance for the convenience of making the explanation simple and easy to understand, so that there is only one type of variable corresponding to the observation luminance y. However, a normal actual image display is a color image. Since luminance unevenness of a color image causes chromaticity unevenness, the luminance unevenness correction takes into account correction of chromaticity unevenness. Since correction of luminance (brightness) corresponding to each of a plurality of types of signal components used for color image display is necessary for correction of chromaticity unevenness, the number of types of signal components can be used as a variable. There are several correspondingly. For example, if an image is displayed using three types of signals corresponding to the three primary colors R, G, and B, the proper idea is to correct the brightness and intensity (luminance) of each RGB color. Thus, three types of variables are required for correcting the levels of the R, G, and B video signals.
In addition, it is difficult to express the transmittance of the liquid crystal panel in actual terms simply by the γ-power as theoretically.

Due to some circumstances as described above, in order to actually correct luminance unevenness, a plurality of sets of two-dimensional correction data described with reference to FIG. 2 are prepared corresponding to each luminance. FIG. 4 schematically shows the structure of such correction data.
As shown in this figure, regarding the correction data, a three-dimensional space of a screen horizontal direction (X direction), a screen vertical direction (Y direction), and a luminance (brightness) direction (Z direction) is set. The two-dimensional correction data set shown in FIG. 2 can be viewed as a reference correction amount table structure according to the horizontal / vertical direction of the screen, and is therefore named “reference correction amount table” in this figure. Here, an example is shown in which the first to third reference correction amount tables are provided according to three different luminances.
At the time of correction processing, an appropriate correction amount in the first to third reference correction amount tables based on the pixel position in the two-dimensional direction and the luminance level (corresponding to the drive voltage level) in the luminance (brightness) direction. Using this information, an interpolation operation is executed to determine a correction amount, and correction processing for the video signal is performed.
As the interpolation processing method, there are a linear interpolation as shown by a solid line in FIG. 5 and a curved interpolation using a predetermined higher-order function as shown by a broken line, for example. is there.

The television receiver 1 according to the present embodiment includes the liquid crystal display unit 18 as a display part as described with reference to FIG. That is, a liquid crystal display device is adopted.
As is well known, a liquid crystal display device is a liquid crystal panel (display panel) comprising a liquid crystal layer and a drive circuit system for driving the liquid crystal of the liquid crystal layer, and for irradiating light from the back side of the liquid crystal panel. It consists of a backlight unit as a light source.
As a backlight unit of the liquid crystal display unit 18 of the present embodiment, LEDs (Light Emitting Diodes) of three primary colors of R (red), G (green), and B (blue) are used as a liquid crystal panel. It is supposed that what was comprised so that a white light may be irradiated by arrange | positioning with respect to the back side of this. Although cold cathode fluorescent lamps have been widely adopted for backlights, LEDs have been used as backlights against the backdrop of the fact that the LED's luminous efficiency has improved, making it practical for use as backlights. It is in a situation where it has been adopted. Advantages when comparing LEDs with cold cathode tubes include that they are good for the environment because mercury is not used as a material, that they can be driven at low voltage, and that they have good temperature and response characteristics. it can.

However, when the LED is employed as a backlight unit as in the present embodiment, the following problems become prominent with respect to luminance unevenness and luminance unevenness correction.
In configuring the LED as a backlight unit, a required number of LEDs are two-dimensionally arranged in a predetermined pattern on the back side of the liquid crystal panel. And it is made to irradiate from the back side of a liquid crystal panel by the two-dimensional irradiation light range obtained by the collection | assembly of these LED.
However, since each LED can be viewed as a point light source, the above-described structure obtains a two-dimensional irradiation light range by a set of point light sources. For this reason, the state of occurrence of luminance unevenness depends on the interval between the arranged LEDs. This means that, for example, the pitch of the luminance unevenness becomes considerably fine as compared with the case where a cold cathode tube is adopted for the backlight.
When the backlight unit is configured by the cold cathode tubes, for example, the required number is configured such that the longitudinal direction thereof is aligned along the screen horizontal direction and the longitudinal direction thereof is aligned along the screen horizontal direction. Or the structure which tries to irradiate the back surface of a liquid crystal panel uniformly by reflecting the light of one cold-cathode tube along one horizontal or vertical direction of a screen using a reflecting plate etc. Take. In the former configuration, the luminance unevenness mainly occurs, for example, between the adjacent cold cathode tubes, and in the latter structure, the luminance unevenness changes according to the distance from the cold cathode tube. .
Thus, in the case of adopting any structure as a backlight employing a cold cathode tube, the cold cathode tube has a shape having a longitudinal direction and becomes a linear light source. It turns out that it becomes a rough thing rather than the case where LED is employ | adopted.

As described above, let us consider correcting the luminance unevenness in response to the fact that the pitch of the luminance unevenness is reduced by adopting the LED backlight unit or the like. Then, for example, the correction points per set of the two-dimensional correction data (reference correction amount table) shown in FIG. 2 are increased according to the pitch of the luminance unevenness, for example, compared to the case where a cold cathode tube is used for the backlight. It will be necessary. This means that the data size of the correction amount forming the reference correction amount table increases. Specifically, although it depends on the size of the liquid crystal panel and the number of pixels, the number of reference correction point areas (FIG. 2) obtained by dividing the entire image in the horizontal / vertical direction, which is required according to the pitch of luminance unevenness. Is about 30 × 16 or 60 × 33. In addition, as a conventional method, a plurality of such reference correction amount tables are provided according to the luminance (brightness) direction, so that the data size for correcting luminance unevenness is considerably enlarged. Will do.
If the data size for correcting luminance unevenness increases, for example, it is necessary to increase the storage capacity of the memory for storing and holding this data, resulting in an increase in cost. Further, since the correction amount data increases, more time is required for adjustment of the correction amount data at the time of manufacturing or the like, resulting in a decrease in manufacturing efficiency.
By adopting LEDs for the backlight and making the pitch of the luminance unevenness fine, such a problem becomes remarkable and cannot be ignored.

Therefore, in this embodiment, as described below, a configuration for correcting luminance unevenness is obtained so that at least the same correction effect can be obtained while reducing the required correction data size. It is supposed to be taken.
For this reason, in the present embodiment, first, only one set corresponding to a specific luminance is provided for the two-dimensional correction data (reference correction amount table) shown in FIG. Conversely, a plurality of sets of reference correction amount tables are not provided corresponding to the luminance (brightness) direction. The reference correction amount table having this structure is held in a predetermined storage unit included in the control unit 19 as shown as a reference correction amount table 19a in FIG.

  However, as described above, in practice, it is difficult to achieve appropriate luminance unevenness correction using correction amount data including only one set of reference correction amount tables. In this regard, the present embodiment is solved by adopting the configuration shown in FIG. 6 or FIG.

6A and 6B show a configuration example of the correction circuit unit 21 provided for correcting luminance unevenness in the television receiver 1 of the present embodiment. In the configuration of FIG. 1, the correction circuit unit 21 is provided at a predetermined signal processing stage in the video signal processing unit 16. Further, the correction circuit unit 21 actually has a configuration corresponding to digital signal processing, and a video signal input as a correction target is also processed in a digital signal format.
Here, as the reference correction amount data forming the two-dimensional correction data (reference correction amount table 19a), the correction amount of the video signal is corrected by addition / subtraction, and the gain coefficient is multiplied. Consider the coefficient format.

FIG. 6A shows a configuration example of the correction circuit unit 21 corresponding to the correction amount in the addition format. The correction circuit unit 21 includes an adder 31 that adds and outputs an input signal (data), and a multiplier 32 that multiplies the input signal and outputs it.
The video signal to be corrected is branched and input to the adder 31 and the multiplier 32. The multiplier 32 multiplies the video signal to be corrected by the correction amount data and outputs the output to the adder 31 . The correction amount data input to the multiplier 32 is obtained by interpolation using the reference correction amount data forming the reference correction amount table in accordance with the pixel position corresponding to the video signal to be corrected. Therefore, the correction amount has a component only in the two-dimensional direction corresponding to the specific luminance, and does not have a component corresponding to the three-dimensional direction (luminance (brightness) direction). Such a correction amount is herein referred to as a “two-dimensional correction amount”.
The adder 31 adds the video signal to be corrected and the calculation output of the multiplier 32 and outputs the result. The output of the adder 31 becomes a video signal after correction processing.

  In the configuration described above, the multiplier 32 multiplies the video signal and the data of the two-dimensional correction amount so that the original video signal corresponding to the level (brightness and brightness) of the video signal is directly applied. A correction amount to be added to or subtracted from is obtained. That is, the correction amount output from the multiplier 32 is obtained by adding a correction amount component corresponding to the luminance of the video signal to be corrected to the two-dimensional correction amount before being input to the multiplier 32. become. That is, the three-dimensional correction amount data has the correction amount components in the screen horizontal direction (X direction), the screen vertical direction (Y direction), and the luminance (brightness) direction (Z direction) described with reference to FIG. Then, the adder 31 adds the three-dimensional correction amount to the original video signal, thereby obtaining a video signal subjected to the correction process.

FIG. 6B shows a configuration example corresponding to the two-dimensional correction amount in the coefficient format as the correction circuit unit 21.
The correction circuit unit 21 obtains a corrected video signal as an output of the multiplier 33 by multiplying the video signal to be corrected by the coefficient format two-dimensional correction amount data by the multiplier 33. To be.

Here, for example, if the data of the two-dimensional correction amount in the addition / subtraction format in the correction circuit unit 21 shown in FIG. 6A is 10 bits, the range of values that can be taken as the correction amount is 0-1023. The negative correction amount can be expressed by a complement, for example. As a specific example, if the value indicated by the 10-bit two-dimensional correction amount data is +102, this is a value that is approximately 10% of the full scale of the video signal level. On the other hand, in the configuration of FIG. 6B, if the value indicating 1.1 times is taken as the two-dimensional correction amount data, the 10-bit two-dimensional correction amount data in the configuration of FIG. The same correction processing result as when +102 is shown can be obtained.
In this way, it is possible to obtain an equivalent correction result in the configurations of FIGS. 6 (a) and 6 (b). Actually, either configuration of FIG. 6 (a) or FIG. 6 (b) may be adopted, whereas the configuration of FIG. 6 (a) includes one adder and one multiplier. Since the configuration of FIG. 6B only needs to include one multiplier, the configuration of FIG. 6B is more advantageous in terms of reduction in circuit scale, cost, and the like.

  In the configuration of the correction circuit unit 21 shown in FIG. 6A, the multiplier 32 multiplies the two-dimensional correction amount and the video signal to be corrected to obtain three-dimensional correction data. Yes. The three-dimensional correction data obtained in this way is obtained by making the two-dimensional correction amount linearly proportional to the level (luminance) of the video signal to be corrected. On the other hand, the correction circuit unit 21 in FIG. 6B directly multiplies the video signal to be corrected by the gain-type two-dimensional correction amount data. The processing result similar to that of the circuit of FIG. 6 (a) can be obtained. Therefore, the correction circuit unit 21 of FIG. Thus, it can be said that the three-dimensional correction amount is obtained in proportion to the linearity, and the correction processing for the video signal is executed with the data of the three-dimensional correction amount.

  However, as can be understood from the description with reference to FIG. 3, the luminance y observed on the display screen is the level of the original video signal due to factors such as the liquid crystal panel transmittance problem. It tends to have nonlinear characteristics with respect to (brightness, luminance). Therefore, in order to obtain a three-dimensional correction amount, it is preferable that the correction circuit unit 21 has a configuration in which the two-dimensional correction amount is non-linearly proportional to the video signal level to be corrected because a better correction result can be expected. become.

FIGS. 7A and 7B show a configuration example of the correction circuit unit 21 configured to perform luminance unevenness correction with a three-dimensional correction amount that is non-linearly proportional to the video signal level to be corrected. .
First, FIG. 7A shows a configuration when the two-dimensional correction amount is in an addition / subtraction format. The configuration shown in this figure is configured by adding a nonlinear circuit 35 to the configuration shown in FIG. The non-linear circuit 35 is provided at the input stage of the multiplier 32 so as to input a video signal to be corrected.
The nonlinear circuit 35 is, for example, a ROM as hardware, and holds nonlinear response characteristics with respect to the video signal level (luminance). Then, the input video signal is provided with a level corresponding to the held non-linear characteristic and output to the multiplier 32. As a result, the three-dimensional correction amount data output from the multiplier 32 has a value obtained by making the two-dimensional correction amount non-linearly proportional to the luminance.

FIG. 7B shows the configuration of the correction circuit unit 21 when the coefficient format is used for the two-dimensional correction amount.
The correction circuit unit 21 shown in FIG. 7B is configured by adding a nonlinear circuit 36 and a multiplier 34 to the configuration shown in FIG. 6B. In this case, the non-linear circuit 36 holds a non-linear characteristic set according to the two-dimensional correction amount in the coefficient format, and converts and outputs the video signal level to be corrected by the non-linear characteristic. Then, this output is output to the multiplier 34.
The multiplier 34 multiplies the output of the non-linear circuit 36 by the coefficient format two-dimensional correction amount data. As a result, the two-dimensional correction amount data is given a non-linear characteristic according to the level of the video signal to be corrected. The multiplier 33 multiplies the data of the two-dimensional correction amount given the nonlinear characteristic and the video signal to be corrected.
In this way, in any of the correction circuit units 21 shown in FIGS. 7A and 7B, the luminance unevenness correction adapted to the non-linear characteristic of the measured luminance y is performed, for example.

  Moreover, regarding the correction circuit unit 21 shown in FIGS. 7A and 7B, any configuration shown in FIGS. 7A and 7B may be employed in practice. However, it is normal that a multiplier has a larger circuit scale and a higher cost than an adder. Therefore, in consideration of the circuit scale and cost, FIG. 7 (a) includes one multiplier and one adder rather than the circuit of FIG. 7 (b) that includes two multipliers. ) Is more advantageous.

By the way, the television receiver 1 of the present embodiment is actually configured to display a color image.
As a general method for displaying a color television image at present, a signal (three primary color signals) corresponding to three primary colors [R (red), G (green), B (blue)] is used. It has been known. Alternatively, a method using a signal based on [Y, Cr, Cb] or [Y, Pr, Pb] as a combination of a luminance signal and a color difference signal is also known. In this way, for any color image display, regardless of which method is employed, any one of [R, G, B] [Y, Cr, Cb] [Y, Pr, Pb] is used. Three types of video signals are used.

Assuming that the television receiver 1 of the present embodiment displays a color image by the above-described color image display method, the basic configuration for correcting luminance unevenness provided in the television receiver 1 is as follows. For example, as shown in FIG.
FIG. 8 shows a luminance unevenness correction unit 20 as a circuit part for correcting luminance unevenness. The luminance unevenness correction unit 20 includes three correction circuit units 21A, 21B, and 21C corresponding to the R, B, and G video signals. These correction circuit units 21A, 21B, and 21C are configured to have the configuration of the correction circuit unit 21 shown in either FIG. 6A, FIG. 6B, or FIG.
In the configuration shown in this figure, R, B, and G video signals for the [R, G, B] system, for example, are input to the correction circuit units 21A, 21B, and 21C, respectively. In both cases, two-dimensional correction amount data for correcting luminance unevenness corresponding to each color of R, B, and G is input to each of the correction circuit units 21A, 21B, and 21C. . That is, for color image display, for example, a correction signal processing system having correction circuit units 21A, 21B, and 21C corresponding to each of R, G, and B video signals is provided, and the two-dimensional correction shown in FIG. As the amount data (reference correction amount table), for example, a configuration is adopted in which three prepared according to each correction processing system of R, G, B video signals are prepared and held.
Further, even when a method other than the [R, G, B] method, such as the [Y, Cr, Cb] method or the [Y, Pr, Pb] method, is adopted as the color image display method, luminance unevenness correction is performed. The unit 20 is provided with a correction processing system including correction circuit units 21A, 21B, and 21C corresponding to each video signal, and then for correcting luminance unevenness corresponding to the display component of each video signal. Dimension correction amount data is prepared and held. The correction circuit units 21A, 21B, and 21C are configured to input two-dimensional correction amount data corresponding to the input video signal to be corrected.
For confirmation, in order to correct luminance unevenness of a color image in the past, a plurality of two-dimensional correction amounts corresponding to the luminance (brightness) direction are provided for each of the three types of video signals. Data (reference correction amount table) is included. In the present embodiment, only one two-dimensional correction amount data (reference correction amount table) corresponding to each of the three types of video signals may be used. Therefore, the data size for luminance unevenness correction is reduced. The effect is not impaired.

  However, as described above, having two-dimensional correction amount data (reference correction amount table) for each of a plurality of types of video signals corresponding to color image display means that luminance unevenness correction is performed from an absolute viewpoint. This means that the data size for doubling depends on the number of types of video signals. Therefore, if it is possible to adopt a configuration in which the luminance unevenness of the color image can be corrected with a smaller number of reference correction amount tables, it is more preferable because the size of the luminance unevenness correction data is further reduced. I can say.

Therefore, in practice, the television receiver 1 of the present embodiment adopts the configuration shown in FIG. In the description of FIG. 9, first, the case where the [R, G, B] method is used is taken as an example.
First, the correction circuit unit 21 includes three correction processing systems including correction circuit units 21A, 21B, and 21C corresponding to R, G, and B. The two-dimensional correction amount data to be input to the correction circuit units 21A, 21, B, and 21C for each of these correction processing systems includes two types of data: a first two-dimensional correction amount and a second two-dimensional correction amount. Only two-dimensional correction amount data is prepared.

The first two-dimensional correction amount data is data of a two-dimensional correction amount created by adjusting to perform luminance unevenness correction for the R color component. The data of the second two-dimensional correction amount is data of a two-dimensional correction amount created by adjusting to perform luminance unevenness correction for the B color component. That is, in the present embodiment, the two-dimensional correction amount data corresponding to the G color component is not used for luminance unevenness correction. Thus, for example, there are only two reference correction amount tables to be stored and held in the memory, corresponding to R and B, and the reference correction amount table corresponding to the G color component is omitted. The data size of the entire correction amount table is further reduced.
Note that the first and second two-dimensional correction amount data in this case may be composed of correction amount data obtained by simply canceling the individual measured luminance differences of R and B. For example, it is formed by correction amount data obtained so as to obtain the best improvement in luminance unevenness when viewed as the entire actual display image while mainly performing R and B luminance unevenness correction. Also good.

9 includes switches SW1, SW2, and SW3 for switching the path through which the first two-dimensional correction amount and the second two-dimensional correction amount are input to the correction circuit unit 21. The switches SW1, SW2 and SW3 are switched in such a way that the switching is performed such that the terminal T1 is alternatively connected to any one of the terminals T2, T3 and T4. It is supposed to be. Terminals T1 of the switches SW1, SW2, and SW3 are connected to correction amount data inputs of the correction circuit units 21A, 21B, and 21C, respectively.
Further, the data of the first two-dimensional correction amount is input to the terminals T2 and T3 of the switch SW1, and the terminal T4 is grounded (conceptually, it may be open).
The data of the second two-dimensional correction amount is input to the terminal T2 of the switch SW2, and the terminal T3 is grounded. The data of the second two-dimensional correction amount is also input to the terminal T4.
The terminal T2 of the switch SW3 is grounded, the second correction amount data is input to the terminal T3, and the first correction amount data is input to the terminal T4.

The patterns of the first two-dimensional correction amount data and the second two-dimensional correction amount data input to the correction circuit units 21A, 21B, and 21C according to the switching state of the switches SW1, SW2, and SW3 are as follows. Become.
First, as the first pattern, when the terminal T2 of the switches SW1, SW2, SW3 is connected to the terminal T1,
Correction circuit unit 21A (corresponding to R) ← first two-dimensional correction amount (corresponding to R)
Correction circuit unit 21B (corresponding to B) ← second two-dimensional correction amount (corresponding to B)
Correction circuit unit 21C (corresponding to G) ← grounding: no correction amount data is input.
Further, as the second pattern, when the terminal T3 of the switches SW1, SW2 and SW3 is connected to the terminal T1,
Correction circuit unit 21A (corresponding to R) ← first two-dimensional correction amount (corresponding to R)
Correction circuit unit 21B (corresponding to B) ← Earth ground: Correction circuit data input 21C (corresponding to G) ← Second two-dimensional correction amount (corresponding to B)
It becomes.
Further, as the third pattern, when the terminal T4 of the switches SW1, SW2 and SW3 is connected to the terminal T1,
Correction circuit 21A (corresponding to R) ← Grounding: Correction circuit without data input 21B (corresponding to B) ← Second two-dimensional correction amount (corresponding to B)
Correction circuit unit 21C (corresponding to G) ← first two-dimensional correction amount (corresponding to R)
It becomes.

9 corrects the first two-dimensional correction amount data corresponding to the R component correction and the second two-dimensional correction amount data corresponding to the B component correction. Input is made to each of two correction circuit units selected from the circuit units 21A, 21B, and 21C. In other words, in the configuration shown in FIG. 9, for example, if the luminance unevenness correction is performed for some of these color components without performing the luminance unevenness correction for each of the R, G, and B color components, for example, a visual problem is caused. On the basis of the fact that the state of brightness unevenness is improved to such an extent that the brightness is eliminated, for example, by correcting the brightness unevenness for two color components of R, B out of R, G, B, the brightness of the entire screen as a result It is intended to obtain the effect of unevenness correction.
In the configuration shown in FIG. 9, based on the fact that the first and second two-dimensional correction amount data correspond to the R and B color components, respectively, the correction circuit unit 21A formed by the first pattern. A route in which the first two-dimensional correction amount (corresponding to R) is input to (R correspondence) and the second two-dimensional correction amount (corresponding to B) is input to the correction circuit unit 21B (corresponding to B) is optimal. It will be. Therefore, in normal times, the signal path may be formed by connecting the terminal T2 to the terminal T1 for the switches SW1, SW2, and SW3.
However, there may be a case where an expected result for luminance unevenness correction under the signal path described above cannot be obtained due to some factor. In such a case, a better correction result may be obtained if the path is based on the second pattern or the third pattern other than the first pattern.
Switching of the switches SW1, SW2, and SW3 should be performed according to such a situation.

  Then, switching of the switches SW1, SW2, and SW3 may be performed, for example, at a timing corresponding to the pixel unit during image display. For this purpose, when creating the reference correction amount table, it is measured and estimated which pattern provides the best correction result for each pixel or image area portion among the first to third patterns. Based on this result, information indicating the correspondence between pixels and patterns is created and held. As the display control, the switch switching control may be executed with reference to this information.

By the way, as the input relationship between the correction circuit unit 21 based on the first to third patterns and the two-dimensional correction amount data, the first two-dimensional correction amount is applied to the correction circuit unit 21C corresponding to the G color component. Data (corresponding to R) and second two-dimensional correction amount data (corresponding to B) may be input (second and third patterns), but for the correction circuit unit 21A corresponding to the R color component, Only when the first two-dimensional correction amount data (corresponding to R) is input or when there is no data input, the second two-dimensional correction amount data (corresponding to B) is not input. Similarly, the second two-dimensional correction amount data (corresponding to B) is input to the correction circuit unit 21B corresponding to the B color component, or only when there is no data input, the first two-dimensional There is no case where correction amount data (R correspondence) is input.
This is because the colors of R and B are complementary to each other. For this reason, it is difficult to correct the luminance unevenness corresponding to the R color component with the correction amount corresponding to the B color component. Similarly, the luminance unevenness corresponding to the B color component is changed to the R color component. It is also difficult to correct with the corresponding correction amount. Therefore, in order to eliminate patterns for which good correction results cannot be expected, only the patterns as described above are prepared and switched.

  Further, when the configuration shown in FIG. 9 is applied to the [Y, Cr, Cb] method, the [Y, Pr, Pb] method, or the like other than the [R, G, B] method, for example, R A Cr or Pr signal is input to the corresponding video signal input, a Cb or Pb signal is input to the video signal input corresponding to B, and a Y signal is input to the video signal input corresponding to G. What is necessary is just to comprise so that a signal may be input.

FIG. 10 shows a block configuration for generating data of first and second two-dimensional correction amounts corresponding to pixel units to be input to the correction circuits 21A, 21B, and 21C.
The two-dimensional correction amount data based on the structure shown in FIG. 2, that is, the reference correction amount table 41 is actually written in a ROM (or EEPROM, flash memory, etc.) that is a storage element as hardware. Will be held. The reference correction amount table 41 here includes two types of tables corresponding to the first two-dimensional correction amount and the second secondary correction amount. That is, the reference correction amount table for correcting the luminance unevenness corresponding to the R color component and the reference correction amount table for correcting the luminance unevenness corresponding to the B color component are formed.

The correction amount calculation circuit 42a generates first two-dimensional correction amount data corresponding to the pixel unit. For this purpose, as described above with reference to FIG. 2, the correction amount calculation circuit 42 a specifies the region between the reference correction points including the pixel position corresponding to the video signal to be corrected, and then in the reference correction amount table 41. A reference correction amount (first reference correction amount) that forms the specified reference correction point region is acquired from the first two-dimensional correction amount (corresponding to R) table. Then, the first two-dimensional correction amount for the video signal corresponding to the pixel position is generated by executing the interpolation processing described in FIG. 2 using the first reference correction amount.
The correction amount calculation circuit 42b also forms the specified reference correction point area from the second two-dimensional correction amount (corresponding to B) table in the reference correction amount table 41 in accordance with the operation of the correction amount calculation circuit 42a. A reference correction amount (second reference correction amount) to be acquired is acquired. Then, interpolation processing is executed using the acquired second reference correction amount to generate second two-dimensional correction amount data.
The first and second two-dimensional correction amount data generated in this way is input to the correction circuit units 21A, 21B, and 21C via the switches SW1, SW2, and SW3 shown in FIG.

  By the way, an image display device that displays an image by a video signal often employs a configuration in which nonlinear processing such as gamma correction is performed on the video signal. For example, gamma correction is performed for the purpose of correcting the luminance characteristics with respect to the voltage of the cathode ray tube on the video signal sending side, as is well known, but at present, on the display output device side, In order to improve contrast such as intermediate luminance, gamma correction is performed so that the gamma nonlinear processing on the transmission side or the non-cancellation characteristics on the display device side is given to the video signal. Such signal processing for contrast enhancement such as gamma correction can be said to be processing for enhancing luminance gradation in a two-dimensional space as an image. Such processing is referred to as space enhancement processing here.

Consider the relationship between the luminance unevenness correction signal processing system of this embodiment and the above-described spatial enhancement system processing.
The luminance unevenness correction process is a process of changing the luminance for correction only in a region where the luminance unevenness of the display device is assumed. If a video signal that has been subjected to such luminance change processing is input and spatial enhancement processing is performed, the luminance change due to luminance unevenness correction causes the correction amount in the spatial enhancement system to be in the direction in which an error occurs. There is a possibility to change. As a result, for example, correction such as gamma correction may be inappropriate, and the display image quality may be deteriorated.
Therefore, when combining the signal processing system for correcting luminance unevenness and the spatial enhancement signal processing system of the present embodiment, the spatial enhancement system signal processing is executed as shown in FIG. The luminance unevenness correction unit 20 is arranged at the subsequent stage of the space enhancement system processing unit 51.
In this way, the luminance change due to the luminance unevenness correction does not affect the nonlinear signal processing in the space enhancement system processing unit 51, and the above-described problem of the correction amount error is solved.

In addition, as the video signal processing, for example, in contrast to the above-described spatial enhancement type signal processing, there may be a case where spatial relaxation type signal processing is applied which has an effect of reducing luminance gradation in a space as an image. For example, processing such as dithering and error diffusion. By performing such processing on the video signal, for example, the contrast in the image space is weakened, and the apparent gradation is increased.
As can be generally said, as described above, the luminance unevenness correction changes the luminance only in the region where the luminance unevenness of the display device is caused. For this reason, when luminance unevenness correction is performed on a video signal that displays a uniform image content as a whole, the area corresponding to the corrected video signal and the correction are not performed. In some cases, the difference in appearance of the luminance of the image from the region corresponding to the video signal may appear to be visually unnatural. Such a phenomenon is more likely to occur as the luminance of the entire screen is lowered.
For this reason, when the signal processing system for correcting luminance unevenness according to the present embodiment and the signal processing system for spatial relaxation are combined, as shown in FIG. It is preferable to arrange a spatial relaxation system signal processing unit 52 that executes spatial relaxation system signal processing in the subsequent stage of 20. By adopting such a configuration, it is possible to suppress or eliminate a luminance difference caused by luminance unevenness correction by the spatial relaxation system signal processing unit 52 in the subsequent stage, and obtain a good display image quality. become.
Note that the spatial enhancement system processing unit 51 and the spatial relaxation system processing unit 52 shown in FIGS. 11A and 11B also correspond to FIG. 1 in the same manner as the luminance unevenness correction unit 20 of the present embodiment. It may be considered that it is included in the video signal processing unit 16.

As a supplement, a configuration example of an adjustment jig system for correcting luminance unevenness is simply shown in FIG.
In this figure, the television receiver 1 of the present embodiment is shown. The television receiver 1 is in the process of adjusting luminance unevenness in the manufacturing process.
In order to adjust the luminance unevenness, for example, an image is displayed on the screen of the liquid crystal display unit 18 of the television receiver 1 by a predetermined video signal for measurement. Then, the displayed image is taken by the camera 60. An imaging signal of an image captured by the camera 60 is input to the correction amount information generation device 61.
The correction amount information generation device 61 is configured to include, for example, a computer system, and measures the state of luminance unevenness on the image area based on the input video signal so that the luminance unevenness can be canceled according to the measurement result. Thus, the correction amount to be given to the video signal is obtained. The correction amount obtained here is, for example, reference correction amount data corresponding to each correction point described with reference to FIG. Then, a predetermined storage unit (for example, ROM, flash memory, etc.) provided in the internal circuit 1a of the television receiver 1 with correction amount information (in the embodiment, a reference correction amount table) formed as a set of reference correction amount data. ) And memorize it. Here, the internal circuit 1a indicates, for example, a set of functional circuit portions shown in FIG.
As can be understood from the adjustment of brightness unevenness as described above, the more correction points, the more time is required for adjustment, and the processing load to be executed by the correction amount information generating device 61 is heavier. It turns out that manufacturing efficiency falls by becoming. Conventionally, with the system shown in FIG. 12, an adjustment work amount (time) for obtaining correction amount data for a plurality of reference correction amount tables corresponding to the luminance (brightness) direction, a processing algorithm, etc. Construction is required. On the other hand, in the present embodiment, it is only necessary to obtain correction amount data for one reference correction amount table corresponding to one specific luminance, and accordingly, the adjustment work amount is small, and correction amount information generation is performed. The processing of the device 61 is also lightened.

As described above, the configuration for correcting the luminance unevenness according to the present invention is effective in a situation where the correction point is increased by adopting the LED for the backlight, but is linearly proportional. Alternatively, the effect that the amount of data for correcting luminance unevenness is reduced by having only the correction amount used in a non-linear proportion includes cathode ray tube display devices, plasma display devices, organic EL (Electro Luminescence) display devices, and the like. The present invention can be obtained similarly when applied to other image display devices in general.
In the above embodiment, each video signal component has only one set of reference correction amount tables corresponding to one specific luminance, but 2 or more per video signal component. It is also possible to have two or more sets of reference correction tables corresponding to the brightness of each. When two or more sets of reference correction tables are provided under the present embodiment, parameters such as a coefficient for linear proportionality or nonlinear proportionality are set according to the luminance for each reference correction table. This is because it is expected to realize luminance unevenness correction with higher accuracy and reliability, such as being able to be set so as to be adapted. In other words, the image quality equivalent to that obtained by performing luminance unevenness correction using a predetermined number of reference correction amount tables with the configuration described with reference to FIGS. When trying to obtain by configuration, the required number of reference correction amount tables can be reduced.

It is a block diagram which shows the structural example of the television receiver as embodiment of this invention. It is a figure which shows the concept of the reference | standard correction amount table of this Embodiment, and the production | generation concept of 2D correction amount data corresponding to a pixel based on the reference | standard two-dimensional correction amount data. It is a figure which shows the relationship between the light emission brightness nonuniformity of a backlight unit, and the brightness nonuniformity correction | amendment observed through a liquid crystal panel. It is a figure which shows the structural concept of the reference | standard correction amount data for brightness | luminance unevenness correction | amendment. It is a figure which shows the concept of the interpolation process for calculating | requiring correction amount data using reference | standard correction data. It is a block diagram which shows the example of a structure of the correction | amendment circuit part made to make two-dimensional correction amount data linearly proportional and to obtain a three-dimensional correction amount. It is a block diagram which shows the example of a structure of the correction | amendment circuit part made to make two-dimensional correction amount data non-linearly proportional and to obtain a three-dimensional correction amount. It is a block diagram which shows the basic composition for the brightness irregularity correction | amendment corresponding to a color image display. It is a block diagram which shows the basic composition for the brightness nonuniformity correction | amendment corresponding to a color image display only by the reference | standard correction amount table according to two types of video signals. It is a block diagram which shows the structure for producing | generating the two-dimensional correction amount data corresponding to every pixel from the data of the reference | standard correction amount of a reference | standard correction amount table. It is a block diagram which shows the suitable arrangement configuration example about a brightness nonuniformity correction | amendment part and a space emphasis type | system | group signal processing part in Embodiment, and the suitable arrangement configuration example about a brightness nonuniformity correction part and a space relaxation type | system | group signal processing part . It is a figure which shows the structural example of the adjustment jig | tool system for brightness nonuniformity correction.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Television receiver, 10 Antenna, 11 Tuner, 12 Decoder, 13 Video signal input terminal, 14 Analog decoder, 15 Switch, 16 Video signal processing part, 17 Display driver, 18 Liquid crystal display part, 19 Control part, 19a Reference correction Amount table, 20 luminance unevenness correction unit, 21, 21A, 21B, 21C correction circuit unit, 31 adder, 32, 33, 34 multiplier, 35, 36 nonlinear circuit, 41 reference correction amount table, 42a, 42b correction amount calculation Circuit, 51 Spatial enhancement processing unit, 52 Spatial relaxation processing unit, 60 camera, 61 correction amount information generating device, SW1, SW2, SW3 switch

Claims (9)

  1. Data for correcting non-uniformity in luminance of an image displayed based on a digital video signal, and a plurality of preset values in the image obtained in accordance with the level of a reference video signal Holding means for holding reference correction amount data which is data indicating a correction amount of a horizontal / vertical position which is a reference correction point;
    The video signal is corrected in accordance with the horizontal / vertical direction and the luminance direction in the image , and the horizontal / horizontal obtained by weighting the reference correction amount data at the reference correction points adjacent in the horizontal / vertical direction for the image. The brightness of the image based on the three-dimensional correction amount data, which is correction amount data for each pixel forming the image, obtained by linearly proportionally adjusting the two-dimensional correction amount data corresponding to the vertical position to the level of the video signal to be corrected. Correction means for performing correction processing for correcting non-uniformity with respect to
    With
    The correction means is
    A multiplier for multiplying the video signal to be corrected by the two-dimensional correction amount data in an addition / subtraction format obtained based on the reference correction amount data;
    An adder that adds the three-dimensional correction amount data that is an output of the multiplier and the video signal to be corrected;
    A display image correction device configured to output the output of the adder as a corrected video signal.
  2. Data for correcting non-uniformity in luminance of an image displayed based on a digital video signal, and a plurality of preset values in the image obtained in accordance with the level of a reference video signal Holding means for holding reference correction amount data which is data indicating a correction amount of a horizontal / vertical position which is a reference correction point;
    The video signal is corrected in accordance with the horizontal / vertical direction and the luminance direction in the image , and the horizontal / horizontal obtained by weighting the reference correction amount data at the reference correction points adjacent in the horizontal / vertical direction for the image. The brightness of the image based on the three-dimensional correction amount data, which is correction amount data for each pixel forming the image, obtained by making the two-dimensional correction amount data corresponding to the vertical position nonlinearly proportional to the level of the video signal to be corrected. Correction means for performing correction processing for correcting non-uniformity with respect to
    With
    The correction means is
    A non-linear circuit configured to give a predetermined non-linear characteristic according to the level of the video signal to be corrected;
    A multiplier for multiplying the output of the non-linear circuit by the two-dimensional correction amount data in an addition / subtraction format obtained based on the reference correction amount data;
    An adder that adds the three-dimensional correction amount data that is an output of the multiplier and the video signal to be corrected;
    A display image correction device configured to output the output of the adder as a corrected video signal.
  3. Data for correcting non-uniformity in luminance of an image displayed based on a digital video signal, and a plurality of preset values in the image obtained in accordance with the level of a reference video signal Holding means for holding reference correction amount data which is data indicating a correction amount of a horizontal / vertical position which is a reference correction point;
    The video signal is corrected in accordance with the horizontal / vertical direction and the luminance direction in the image , and the horizontal / horizontal obtained by weighting the reference correction amount data at the reference correction points adjacent in the horizontal / vertical direction for the image. The brightness of the image based on the three-dimensional correction amount data, which is correction amount data for each pixel forming the image, obtained by making the two-dimensional correction amount data corresponding to the vertical position nonlinearly proportional to the level of the video signal to be corrected. Correction means for performing correction processing for correcting non-uniformity with respect to
    With
    The correction means is
    A non-linear circuit configured to give a predetermined non-linear characteristic according to the level of the video signal to be corrected;
    A first multiplier for multiplying the output of the nonlinear circuit by the two-dimensional correction amount data in a coefficient format obtained based on the reference correction amount data;
    A second multiplier that multiplies the three-dimensional correction amount data that is the output of the first multiplier and the input video signal to be corrected;
    A display image correction device configured to output the output of the second multiplier as a corrected video signal.
  4. The video signal to be corrected is composed of three primary color signals or a combination of a luminance signal and two color difference signals.
    The holding means has two kinds of correction data corresponding to two predetermined signals of the three primary color signals or two predetermined signals of the luminance signal and the two color difference signals. Holds 2D correction amount data,
    The correction means includes a correction processing system that performs correction processing corresponding to each of the signals constituting the three primary color signals or each of the luminance signal and the two color difference signals. One of the two types of two-dimensional correction amount data is selected and input to each of the systems.
    The display image correction apparatus according to claim 1.
  5.   4. The display image correction apparatus according to claim 1, wherein the correction unit is provided at a subsequent stage of a gamma correction processing unit that emphasizes luminance gradation of the display image.
  6.   The display image correction apparatus according to claim 1, wherein the correction unit is provided in a preceding stage of a dither or an error diffusion processing unit that reduces the luminance gradation of the display image.
  7. A display image correction device unit, and a display device unit that displays an image based on a video signal subjected to correction processing by the display image correction device,
    The display image correction device section is
    Data for correcting non-uniformity in luminance of an image displayed based on a digital video signal, and a plurality of preset values in the image obtained in accordance with the level of a reference video signal Holding means for holding reference correction amount data which is data indicating a correction amount of a horizontal / vertical position which is a reference correction point;
    The video signal is corrected in accordance with the horizontal / vertical direction and the luminance direction in the image , and the horizontal / horizontal obtained by weighting the reference correction amount data at the reference correction points adjacent in the horizontal / vertical direction for the image. The brightness of the image based on the three-dimensional correction amount data, which is correction amount data for each pixel forming the image, obtained by linearly proportionally adjusting the two-dimensional correction amount data corresponding to the vertical position to the level of the video signal to be corrected. Correction means for performing correction processing for correcting non-uniformity with respect to
    With
    The correction means is
    A multiplier for multiplying the video signal to be corrected by the two-dimensional correction amount data in an addition / subtraction format obtained based on the reference correction amount data;
    An adder that adds the three-dimensional correction amount data that is an output of the multiplier and the video signal to be corrected;
    An image display device configured to output the output of the adder as a corrected video signal.
  8. The display unit is
    A display panel on which an image based on a video signal is displayed, and a light source that emits light from the back side of the display panel,
    The image display device according to claim 7.
  9. Data for correcting luminance non-uniformity for an image displayed based on a digital video signal, and a plurality of preset standards in the image obtained corresponding to the reference video signal level A reading procedure for reading out the reference correction amount data, which is data indicating the correction amount of the horizontal / vertical position as the correction point, from the holding means for holding the reference correction amount data;
    A two-dimensional correction amount data acquisition procedure for obtaining two-dimensional correction amount data corresponding to horizontal / vertical positions obtained by weighting reference correction amount data at reference correction points adjacent in the horizontal / vertical direction for the image ;
    Three-dimensional correction amount data acquisition procedure for obtaining three-dimensional correction amount data, which is correction amount data for each pixel forming the image, obtained from the two-dimensional correction amount data at the level of the video signal to be corrected;
    A correction procedure for performing correction processing for correcting non-uniformity of the brightness of the image based on the three-dimensional correction amount data;
    Run
    The three-dimensional correction amount data acquisition procedure includes a multiplication procedure for multiplying the video signal to be corrected by the two-dimensional correction amount data in the addition / subtraction format obtained based on the reference correction amount data,
    An addition procedure for adding the three-dimensional correction amount data that is the output of the multiplication procedure and the video signal to be corrected is executed, and the output of the addition procedure is output as a corrected video signal. Display image correction method.
JP2006196669A 2005-09-29 2006-07-19 Display image correction apparatus, image display apparatus, and display image correction method Expired - Fee Related JP4770619B2 (en)

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TW095133276A TW200715874A (en) 2005-09-29 2006-09-08 Display image correcting device, image display device, and display image correcting method
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